Decision making is fundamental to all aspects of flying operations. The results that flow from poor aeronautical decision making can be both swift and devastating.

The work of this thesis uses data from a variety of sources to investigate the following aspects of aeronautical decision making;

• accident and incident case histories and pilot decision making

• case-based versus rule-based pilot decision training

• pilot behaviours in the face of adverse weather

The first part of thesis uses survey data to gain a better understanding of the role of accident and incident case histories in aviation safety and training. Anecdotal evidence suggests that exposure to case-based information can leave a lasting impression on a pilot and significantly influence their flying behaviour. To investigate this aspect more formally, information was obtained from a survey of 138 pilots. A questionnaire was then distributed to pilots worldwide and responses were received from 409 pilots, from all areas of aviation. The combined experience of pilots who responded was over 700,000 hours flying time.

The second part of the thesis uses experimental data to compare the effectiveness of aviation safety training using case-based material or rulebased material. Two experiments were carried out, based on the two areas that account for the majority of fatal general aviation accidents: flight into adverse weather and low flying. A total of 114 participants took part in the experimental studies.

The third part of the thesis is based on a set of 491 aviation accident and incident reports drawn from the Australian Transport Safety Bureau occurrence database. The study compares three groups of pilots who differed in their response to adverse weather conditions, as demonstrated by the following behaviours;

• VFR flight into IMC

• a weather-related precautionary landing

• some other significant weather avoidance action

A number of common themes emerged from the three parts of the thesis.

There is strong support for the importance of case-based material in aviation safety and training. However, the results also suggest that aeronautical decision making can be best understood in terms of a model that combines both case-based and rule-based reasoning. Rule-based material provides a basic framework of standard procedures and recommended practices, particularly for novices, while case-based material adds detail and salience to the framework, particularly in the form of affective markers linked to particular case histories.

One important aspect of the results can be summed up by the adage that 'a safe pilot is a proactive pilot'. That is, it is imperative for a pilot to take control of the situation before the situation takes control of them. The results also emphasise the dynamic nature of aeronautical decision making. A pilot may make a series of good decisions, but that is no automatic protection against a subsequent poor decision putting the safety of the flight at risk. Hence, it is critical that a pilot does not fly to the limit of their abilities, or let past success breed complacency.